Synopsis

DESCRIPTION

The Ganeti software manages physical nodes and virtual instances of a
cluster based on a virtualization software. The current version (2.3)
supports Xen 3.x and KVM (72 or above) as hypervisors, and LXC as an
experimental hypervisor.

Quickstart

First you must install the software on all the cluster nodes, either
from sources or (if available) from a package. The next step is to
create the initial cluster configuration, using gnt-clusterinit.
Then you can add other nodes, or start creating instances.

Clusterarchitecture

In Ganeti 2.0, the architecture of the cluster is a little more
complicated than in 1.2. The cluster is coordinated by a master daemon
(ganeti-masterd(8)), running on the master node. Each node runs (as
before) a node daemon, and the master has the RAPI daemon running too.
Noderoles
Each node can be in one of the following states:
master Only one node per cluster can be in this role, and this node is
the one holding the authoritative copy of the cluster
configuration and the one that can actually execute commands on
the cluster and modify the cluster state. See more details under
Clusterconfiguration.
master_candidate
The node receives the full cluster configuration (configuration
file and jobs) and can become a master via the gnt-clustermaster-failover command. Nodes that are not in this state cannot
transition into the master role due to missing state.
regular
This the normal state of a node.
drained
Nodes in this state are functioning normally but cannot receive
new instances, because the intention is to set them to offline
or remove them from the cluster.
offline
These nodes are still recorded in the Ganeti configuration, but
except for the master daemon startup voting procedure, they are
not actually contacted by the master. This state was added in
order to allow broken machines (that are being repaired) to
remain in the cluster but without creating problems.
Nodeflags
Nodes have two flags which govern which roles they can take:
master_capable
The node can become a master candidate, and furthermore the
master node. When this flag is disabled, the node cannot become
a candidate; this can be useful for special networking cases, or
less reliable hardware.
vm_capable
The node can host instances. When enabled (the default state),
the node will participate in instance allocation, capacity
calculation, etc. When disabled, the node will be skipped in
many cluster checks and operations.
NodeParameters
These parameters are node specific and can be preseeded on node-group
and cluster level.
Currently we support the following node parameters:
oob_program
Path to an executable used as the out-of-band helper as
described in the Ganeti Node OOB Management Framework (design-
oob.rst) design document.
Clusterconfiguration
The master node keeps and is responsible for the cluster configuration.
On the filesystem, this is stored under the /var/ganeti/lib directory,
and if the master daemon is stopped it can be backed up normally.
The master daemon will replicate the configuration database called
config.data and the job files to all the nodes in the master candidate
role. It will also distribute a copy of some configuration values via
the ssconf files, which are stored in the same directory and start with
a ssconf_ prefix, to all nodes.
Jobs
All cluster modification are done via jobs. A job consists of one or
more opcodes, and the list of opcodes is processed serially. If an
opcode fails, the entire job is failed and later opcodes are no longer
processed. A job can be in one of the following states:
queued The job has been submitted but not yet processed by the master
daemon.
waiting
The job is waiting for for locks before the first of its
opcodes.
canceling
The job is waiting for locks, but is has been marked for
cancellation. It will not transition to running, but to
canceled.
running
The job is currently being executed.
canceled
The job has been canceled before starting execution.
success
The job has finished successfully.
error The job has failed during runtime, or the master daemon has been
stopped during the job execution.

Commoncommandlinefeatures

Options
Many Ganeti commands provide the following options. The availability
for a certain command can be checked by calling the command using the
--help option.
gnt-...command [--dry-run] [--priority {low | normal | high}]
The --dry-run option can be used to check whether an operation would
succeed.
The option --priority sets the priority for opcodes submitted by the
command.

Fieldformatting

Multiple ganeti commands use the same framework for tabular listing of
resources (e.g. gnt-instancelist, gnt-nodelist, gnt-grouplist, gnt-debuglocks, etc.). For these commands, special states are denoted via
a special symbol (in terse mode) or a string (in verbose mode):
*,(offline)
The node in question is marked offline, and thus it cannot be
queried for data. This result is persistent until the node is
de-offlined.
?,(nodata)
Ganeti expected to receive an answer from this entity, but the
cluster RPC call failed and/or we didn't receive a valid answer;
usually more information is available in the node daemon log (if
the node is alive) or the master daemon log. This result is
transient, and re-running command might return a different
result.
-,(unavail)
The respective field doesn't make sense for this entity; e.g.
querying a down instance for its current memory 'live' usage, or
querying a non-vm_capable node for disk/memory data. This result
is persistent, and until the entity state is changed via ganeti
commands, the result won't change.
??,(unknown)
This field is not known (note that this is different from entity
being unknown). Either you have mis-typed the field name, or you
are using a field that the running Ganeti master daemon doesn't
know. This result is persistent, re-running the command won't
change it.
Key-valueparameters
Multiple options take parameters that are of the form
key=value,key=value,... or category:key=value,.... Examples are the
hypervisor parameters, backend parameters, etc. For these, it's
possible to use values that contain commas by escaping with via a
backslash (which needs two if not single-quoted, due to shell
behaviour):
# gnt-instance modify -H kernel_path=an\\,example instance1
# gnt-instance modify -H kernel_path='an\,example' instance1

Commondaemonfunctionality

All Ganeti daemons re-open the log file(s) when sent a SIGHUP signal.
logrotate(8) can be used to rotate Ganeti's log files.

COPYRIGHT

Copyright (C) 2006, 2007, 2008, 2009, 2010 Google Inc. Permission is
granted to copy, distribute and/or modify under the terms of the GNU
General Public License as published by the Free Software Foundation;
either version 2 of the License, or (at your option) any later version.
On Debian systems, the complete text of the GNU General Public License
can be found in /usr/share/common-licenses/GPL.